Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .CD20 is a transmembrane non-glycosylated phosphoprotein acting as receptor during B-cell activation and differentiation. In the ontogeny of B lymphoid cells,CD20 is present in B cells after CD19 in the naïve B-lymphocytes and remains until late stages of B-lymphocyte differentiation but disappears in the plasma cell stage. Together with CD79a, CD20 is one of the most important marker for the identification of B-cell neoplasms and also used to plan further treatment.